Semiconductor device including bit line formed using damascene technique and method of fabricating the same

1. A method of fabricating a semiconductor device, the method comprising:

forming an insulating layer over a substrate;

forming a groove by etching the insulating layer to a partial depth;

forming spacers on inner walls of the groove;

forming an opening in the insulating layer by etching the insulating layer disposed under the groove by using the spacers as an etch mask;

forming a conductive layer in the opening; and

forming a mask in the groove with said spacers, wherein forming the conductive layer comprises:

forming a conductive layer to completely fill the opening and the groove; and

etching the conductive layer using an etchback process to below the bottom of the spacers.

2. A method of fabricating a semiconductor device, the method comprising:

forming an insulating layer over a substrate;

forming a groove by etching the insulating layer to a partial depth;

forming spacers on inner walls of the groove;

forming an opening in the insulating layer by etching the insulating layer disposed under the groove by using the spacers as an etch mask;

forming a conductive layer in the opening; and

forming a mask in the groove with said spacers, wherein forming the conductive layer comprises:

forming a conductive layer to completely fill the opening and the groove; and

wet-stripping the conductive layer to below the bottom of the spacers.

3. A method of fabricating a semiconductor device, the method comprising:

forming gate stacks and source/drains over a substrate;

forming a first insulating layer to fill a gap between the gate stacks;

planarizing the first insulating layer;

forming a first cell pad and a second cell pad in the first insulating layer, the first cell pad and the second cell pad being connected to each source and each drain, respectively;

forming a second insulating layer over the first insulating layer and the first cell pad and the second cell pad;

forming a bit line contact plug in the second insulating layer to contact the second cell pad;

forming a third insulating layer over the second insulating layer and the bit line contact plug;

forming a mask pattern over the third insulating layer;

forming a groove by etching the third insulating layer to a partial depth using the mask pattern as an etch mask;

forming spacers on the inner walls of the groove;

forming a bit line opening, which exposes the bit line contact plug, by etching the third insulating layer disposed under the groove using the spacers and the mask pattern as an etch mask;

forming a bit line conductive layer that fills the bit line opening below the bottom of the spacers; and

forming a bit line capping layer that fills the groove so that its top surface is as high as that of the third insulating layer.

4. The method of claim 3 , wherein depositing the third insulating layer comprises forming an etch stop layer using silicon nitride followed by forming a silicon oxide layer.

5. The method of claim 3 , wherein forming the spacers comprises:

forming a silicon nitride layer over the third insulating layer so as not to completely fill the groove; and

etching the silicon nitride layer using an anisotropic etch process until the top surface of the mask pattern and the bottom of the groove are exposed.

6. The method of claim 3 , wherein forming the bit line conductive layer comprises:

forming a conductive layer that completely fills the bit line opening and the groove; and

etching the conductive layer using an etchback process to below the bottom of the spacers.

7. The method of claim 3 , wherein forming the bit line conductive layer comprises:

forming a conductive layer to completely fill the bit line opening and the groove; and

wet-stripping the conductive layer to below the bottom of the spacers.

8. The method of claim 3 , wherein the conductive layer is formed of a Ti layer, a TiN layer, and a W layer, which are sequentially stacked.

9. The method of claim 3 , wherein an interface between the spacers and the third insulating layer is flat.

10. The method of claim 3 , wherein forming the bit line capping layer comprises:

forming a silicon nitride layer over the substrate where the bit line conductive layer is formed to completely fill the groove; and

etching the silicon nitride layer using an etchback process or a chemical mechanical polishing process until the top surface of the third insulating layer is exposed.

11. The method of claim 3 , wherein the dimension of the opening is adjusted by controlling the width of the spacers.